condition mean min max ZT0-3 18.237575 16.8381 19.637050000000002 ZT4-7 20.217 20.217 20.217 ZT8-11 14.30185 14.30185 14.30185 ZT12-15 0 0 0 ZT16-19 16.17385 16.17385 16.17385 ZT20-23 17.7283 17.7283 17.7283